Fastener arresting device for a power actuated tool



Feb. 6, 1962 R, J, KOPF ETAL 3,019,440

FASTENER ARRESTING DEVICE FOR A POWER ACTUATED TOOL 3 Sheets-Shea?l 1 Filed Jan. l2, 1955 /NVf/V70RS Row/and d Kopf 03er Marsh 77M M QM ATTORNEYS Feb. 6, 1962 Filed Jan. l2, 1955 R. J. KOPF ETAL FASTENER ARRESTING DEVICE FOR A POWER ACTUATED TOOL 3 Sheets-Sheet 2 /V Vf /V T ORS Row/ana d /fqnf Roger Mars/7 BY A TTOR/VEY' Feb. 6, R. J KOPF ETAL FASTENER ARRESTING DEVICE FOR A POWER ACTUATED TOOL Filed Jan. 12, 1955 3 Sheets-Sheet 3 INVENTORS Row/and d. Kopf Roger Mars/1 /ToRA/y This invention relates to improvements in power actuated tools and more particularly to a power actuated tool having a captive driveable unit.

One of the objects of the present invention is to provide a power actuated tool wherein a fastener driven thereby cannot escape into free tlight.

A further object of the present invention is to provide a power actuated tool for driving a fastener into a workpiece wherein the fastener is a captive within the tool While it s being driven but in which means are provided for detachment from the tool of at least the piercing portion after driving thereof with the fastener remaining firmly embedded in the workpiece.

A further object of the present invention is to provide a power actuated tool for driving the piercing portion of a fastener into a workpiece wherein said tool includes an abutment means having energy absorbing means to absorb the energy of the driven fastener and to prevent overdriving of said fastener.

A further object of the present invention is to provide a power actuated tool for driving a fastener into a workpiece with said tool preventing the escape of the driven fastener into free flight, preventing overdriving of a driven fastener into soft or relatively less resistant materials, limiting free movement of a driven fastener if it is deformed upon contact with the workpiece, and minimizing likelihood of injury to personnel using or observing the tool without using expendable parts in the tool or parts vulnerable to damage if the tool is mishandled.

A further object of the present invention is to provide a power actuated tool with a resiliently loaded abutment means movable to an operative position for stopping free flight of a driveable unit in the tool as said tool moves into firing position and movable to an inoperative position for releasing said drivable unit as said tool moves into an inactive position.

A further object of the present invention is to provide a power actuated tool characterized by its greater safety in operation, more satisfactory driving of fasteners thereby, structural simplicity, and ease of operation.

Other features of this invention reside in the arrangement and design of the parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from the accompanying drawings and description mld the essential features will be set forth in the appended claims.

In the drawings:

FIG, l is a side elevational view of an explosive type power-actuated tool, partially in section, with a spring mounted catcher block mounted on the barrel muzzle thereof and with the tool shown in the ring pin uncooked position;

FIG. 2 is a longitudinal sectional view of the front portion of the tool in FIG. l pressed against the workpiece into a firing position with a driveable unit driven into a workpiece to its normal depth of penetration;

FIG. 3 is a perspective view of the catcher block in the position shown in FiG. l while the tool is being removed from the driven driveable unit;

Yttes atent fice FIG. 4 is a longitudinal sectional view of a second form of catcher block and eXplosively-actuated tool;

FIG. 5 is an end View of the tool in FIG. 4 looking toward the left at the right end thereof with the catcher block in the driveable unit releasing or its inoperative position;

FIG. 6 is an end view, similar to FIG. 5, but with catcher block in the driveable unit capturing or its operative position;

FIG. 7 is a longitudinal sectional view taken along the line 7--7 in FIG. 6 with the tool pressed against the workpiece in tiring position and the driveable unit driven to its normal penetration depth;

FIG. 8 is a transverse sectional view taken along the line 8 3 of FlG. 7;

FIG. 9 is a longitudinal sectional view, similar to FIG. 7, but with dotted lines omitted for clarity and wherein the operator has attempted to tire the driveable unit into material having insuicient resistance to penetration and the tool prevents free flight thereof;

FIG. l0 is a longitudinal sectional view of a third form of fastener arresting device adapted to be used on a tool of the type shown in FIG. l with the tool in the loaded position;

FiG. l1 is a transverse sectional View taken along the line 11--11 in FIG. 10;

FIG. l2 is a longitudinal sectional view similar to FIG. 10 with the fastener driven to its normal depth of penetration;

FlG. 13 is a longitudinal sectional view similar to FIG. 12 with the fastener driven into material having insuficient resistance to penetration; while FiG. 14 is a longitudinal sectional view similar to FIG. 10 but of a fourth form of fastener arresting device adapted to be used on a tool of the type shown in FIG. l.

Before the tool here illustrated is specifically described, it is to be understood that the invention here involved is not limited to the structural details or arrangements of parts here shown since tools embodying the present invention may take various forms. It also is to be understood that the phraseology or terminology herein employed is for purposes of description and not of limitation since the scope of the present invention is denoted by the appended claims.

Those familiar with this art will recognize that this invention may be applied in many ways. The invention, in its broader aspects, includes al1 types of power actuated tools with power actuation for such fastener driving tools including hydraulic, pneumatic, electromagnetic, eXplosive powder charge, or any other suitable type power. However, only the explosively actuated tool embodiment is described in detail herein. Tool 10 in FIG. l, for eX- amule, is adapted to drive or set a fastener into the at surface of a workpiece 11.

EXplosively-actuated tool i@ in FIG. 1 includes a member with a passageway for confining and driving, such as the bore 15e of barrel 15, so that an explosive charge set off by trigger 16 can drive a driveable unit through the barrel or along any suitable passageway from the breech or entry end toward the barrel muzzle: or discharge end and into workpiece 11. An eXample of an explosively-actuated tool on which the present invention may be used is disclosed in the copending US. patent application entitled Explosively-Actuated Tools, Serial No. 355,034, filed on May 14, 1953 by R. l. Kopf, R. W. Henning and R. Marsh, now U.S. Patent No. 2,945,236 granted July 19, 1960.

In the aforementioned copending application entitled Explosively Actuated Tools to which reference may be had for further disclosure if necessary, tool 10 in FIG. 1 has the ash shield and its sleeve in said cepending application eliminated but includes a housing 14 with a sleeve portion Ma telescopically connected over barrel with said sleeve and barrel being mounted for axial relative movement but keyed against relative rotative movement in the manner disclosed in said copending application, for example. Housing f4- has a firing means therein including a firing pin 18, biased forwardly toward the barrel muzzle into an uncooked position by compression spring I9, movable endwise in said housing between a rearward, cocked or active position and a forward uncooked or inactive position for respectively being capable or incapable of setting off the explosive charge in cartridge case I7. When the barrel muzzle on tool It? is pressed axially against workpiece 11, sleeve 14a telescopes forwardly from the FIG. l uncooked position to the FIG. 2 cocked position. In the movement to such position, a pin 15a carried by the barrel is engaged by a laterally projecting firing pin pawl 2t) on ring pin i8 to cock said firing pin against the bias of spring 19. Trigger 16, pivotally mounted on housing 14, has a sear 16a for depressing firing pin pawl against the bias of its spring 21 to release it from pin 15a. This serves as a means for manually releasing firing pin 18 in cocked position so that its spring 19 can force it forwardly to set off the charge in cartridge i7. When tool I@ is removed `from workpiece 11, spring 24 between housing Id and barrel i5 serves as a means for normally biasing apart barrel 15 and housing 14 into the uncooked safety position shown in FIG. l.

In a conventional explosiveiy actuated tool, the fastener is driven through the barrel and out of the muzzle at high speed, so that if the tool barrel is not properly set against the workpiece or if the fastener is fired into unsuitable material, the fastener may escape into the `air in free flight so as to become a dangerous projectile. It is therefore desirable for safety reasons to prevent the escape of the fastener into free flight. This difliculty may occur when using a conventional tool if the operator attempts to fire the tool into the air instead of against the workpiece, if the operator attempts to fire the tool into a workpiece having insufficient penetration resistance so that the fastener travels completely through the workpiece to escape into free flight, if the operator fires the tool with the barrel axis substantially less than 90 with respect to the surface of the workpiece so that a ricochet occurs, etc. The present invention has solved these, as well as many other problems by having a driveable unit, including the fastener as well as a captive ram or fastener carrier piston, driven through the tool barrel by the explosively actuating gases with this ram prevented by appropriate means from escaping completely from the barrel. Hence, the fastener cannot escape into free flight to become a dangerous projectile.

In the present disclosure, the tool I@ has in FIGS. 13 a captive driveable unit 34) including fastener 31 detachably connected by screw threads to a fastener carrier, such as the element 32 here shown, which is designated herein as a piston, head or ram. The fastener has a forwardly projecting piercing portion 31a for penetrating the workpiece after being driven through the barrel while the piston has an abutment means or shoulder 32a to be described in further detail hereinafter. The ram or piston is shown as being internally threaded to accept the fastener, but in the event any fastener has an internally threaded head, its ram or piston may be externally threaded to engage the fastener.

The safety features of the present invention are not required under normal conditions when there is no danger of having the fastener escape into free flight. During tool loading, the piston 32 in FIGS. 1 3 is screwed onto the thread of fastener 3l so as to form the driveable unit 30 and then this unit is inserted into the breech of the tool barrel 15. It will also be apparent hereinafter that the tool could be loaded from the muzzle instead of the breech, if so desired. Then, an explosive charge, such as cartridge 17 in FIGS. l-3, is also inserted into the breech after which the breech of the tool is closed so that the tool can be moved to tiring position against the workpiece 11, as shown by the tool in FIG. 2. After trigger 16 is pulled, the fastener is driven by the tool into the workpiece to its normal and desired penetration shown in FIG. 2 wherein the front shoulder 32C on the ram rather than abutment shoulder 32a normally limits the penetration thereof, when the parameters of fastener size, powder load and workpiece resistance are not quite suicient to do it alone.

The driveable unit may be held in the barrel bore close to the cartridge 17 in any suitable manner if necessary before the tool is fired so as to control the size of the initial explosive charge chamber and to properly drive the fastener. This may take the form of friction between barrel I0 and piston 32 or other suitable retaining means, and this is especially desirable when .the barrel is pointed downwardly, as in FIG. 2, so as to hold the fastener carrier piston against axial downward movement under only the weight of the driveable unit.

However, if the tool is tired so that there is a possibility of having the fastener escape into free Hight to become a dangerous projectile, the safety feature prevents this normal occurrence by engagement between suitable abutment means when the driveable unit in any of these tools attempts to travel outwardly through the barrel substantially beyond the FiG. 2 position. The tool barrel has a bore ide of uniform diameter throughout most of its length of a size to permit free passage of the driveable unit therethrough with no excess clearance. However, means is provided to arrest the forward travel of the piston or ram while permitting free passage of the piercing portion of the fastener for workpiece penetration. This means includes an abutment means on the tool capable of coacting with the abutment means 32a on the piston or ram to prevent further axial travel of the driveable unit through the barrel and thus to pre- Vent the free escape of the driveable unit from the tool. Hence, the driveable unit is stopped as its piercing portion 31a emerges a predetermined distance beyond the barrel muzzle so as to control the penetration of the workpiece or travel beyond the muzzle independently of the resistance to penetration of the workpiece material or of the explosive driving force.

This abutment means and its operative connection to the tool may take various forms. In FIGS. 1 3, block 36 is mounted over the barrel muzzle and has a barrel bore continuation 36e with an integral, inwardly directed ange 36a, adapted to engage the piston shoulder 32a to prevent overtravel of unit 30. Helical extension spring 23 is telescoped over the barrel and screwed into helical grooves in block 36 and into grooves formed in an outwardly extending flange 15b. A pin 37 in FIG. l carried by block 36 normally travels in longitudinal groove 14b in the bore of sleeve 14E-a when the tool is moved from the FIG. 1 to FIG. 2 positions. This connection prevents axial movement of the tool to the FIG. 2 tiring position unless block 36 is screwed onto spring 23 until pin 37 and slot Mb register to assure proper mounting of block 36 on barrel f5 and assure constant barrel length for accurate angle fire control, as discussed hereinafter relative to the tool in FIGS. 4-9.

This construction provides greater safety in tool operation as well as more satisfactory setting of the fasteners. It prevents the free escape of a fastener. The tool operator cannot dangerously fire the fastener into free flight, as a dangerous projectile, by ring the tool into the air instead of against the workpiece. If the workpiece does not have suiiicient resistance to penetration, there exists neither the danger that the fastener will emerge from the other side of the workpiece as a projectile in free flight nor the danger that the fastener will be overdriven beyond the depth control established by the engagement of the abutment shoulder 32a on the driveable unit and flange 36a at the barrel muzzle. Substantial inclination of the barrel bore from the normal to the workpiece surface will not cause a ricochet since the tool preferably has said angle tire control at excessive inclination and, in any event, the fastener cannot escape into free ilight.

When the fastener' is driven either to the normal penetration position of FIG. 2 or is driven lbeyond this point until the abutments formed by members 32a and 36a engage, the driveable unit 3d in FIGS. l-3 can be removed frorn the bore extension 36e ofthe tool while the fastener remains embedded in the workpiece.

As shown in FIG. 2, the axial thickness of flange 36a of block 36 is somewhat less than the axial spacing of faces 32a and 32C of the piston or ram 32 shown separately in FIG. 3.

In FIGS. l3, both the fastener 3i and the fastener carrier piston or captive ram 32 are easily disengaged as a unit from the tool after tiring. In FIGS. l-3, a transverse opening or side port 36h in the barrel block 3d leads laterally from the barrel bore extension 36e immediately above the shelf formed by the flange 36a to the outside of the barrel. This side port serves as a means for detaching the tool from the driven driveable unit after the driveable unit has stopped traveling through the barrel bore and the parts have returned to the position shown in FIG. l by the operator releasing the pressure on the housing, thus permitting spring 24 to cause the barrel and the housing to occupy an extended position. When the driveable unit has been driven sufficiently far so that the abutment means engage, the captive ram or piston 32 is laterally aligned with the port so that the tool is easily removed by laterally withdrawing the tool therefrom. Sleeve 14a in FIG. l serves as a means for convering port 36h in the firing position of FIG. 2 to protect the operator and for uncovering port 36h for driveable unit removal in the inactive position of FIG. 1 off workpiece l1 responsive to tool movement between these positions.

When block 36 is not assembled on the tool, it should be noted that spring 2.3 in FIG. 2 does not extend far enough forward so that it can be used to move the tool into liring position. Hence, the tool cannot be tired in unsafe condition without block 36.

Gas ports 15d in FIG. 2 are preferably provided in the tool barrel to permit gas escape from behind piston 32 before unit d reaches the FG. 2 position so as not only to reduce the likelihood of high and dangerous pressures developing in the tool barrel but also to minimize tool lift oft the workpiece caused by the expanding pressure of the gas acting against spring 23 in the barrel bore tending to move the tool if the unit Sii stops before the abutment means engage.

The tool in FIGS. 4 to 9 will be next described. Captive driveable unit 3d therein has the same structure and mode of operation as unit 3ft in FIGS. l-3. The unit and cartridge I7 may be loaded into the tool and the unit held in the barrel bore close to cartridge I7 in any suitable manner, such as mentioned for the FIGS. l-3 tool form. An abutment i eans on the tool coacts with the abutment means 32a on the piston or ram as the unit attempts to travel substantially beyond the FIG. 7 position in the same manner as when unit 36 attempts to travel beyond the FIG. 2 position.

The abutment means and its operative connection to the tool takes another form in FIGS. 4-9. Block 46 (corresponding to block 35 iu FIG. l) is mounted over the barrel muzzle with an integral, inwardly directed flange 46a, adapted to engage piston shoulder 32a to prevent overtravel of unit 30. Helical extension spring 23 is telescoped over the barrel and screwed into helical grooves in block 46 and into grooves formed in an extending flange on the tool barrel (similar to flange la in FIG. l but not shown).

Spring 23 operatively connects block 46 to a modified form of barrel 45 for rotation of said block about an axis parallel to the axis of the olf-center bore in barrel 45.

A modified form of sleeve 44a has a continuous slot or groove 44b in the bore thereof and at least partially helical in form for receiving a projecting pin 47 ou block 46 to form a helical cam connection for rotating block 46 on barrel 45 in response to axial movement of sleeve 44a. Block 46 has circumferentially spaced apart thereon about its axis of rotation in FIGS. 5 and 6 one cutout having its edge forming the abutment means on the tool by flange den and a second cut-out 46d larger than the barrel bore with each registerable with the barrel bore in dierent positions of rotation. Hence, flange 46a is operatively mounted on the barrel for movement into either an operative position (FIG. 6 or 7) in alignment with the barrel bore so as to be in the path of travel of the driveable unit 30 and its abutment surface 32a thereon to be effective for stopping said unit or an inoperative position (FIG. 4 or 5) out of said path and out of alignment with the barrel bore to permit removal of unit 3@ therefrom after the fastener has been driven. Movement of the tool sleeve axially over the barrel causes flange 46a of block 4e through ring 43 to move between said positions by the operative connection therebetween. In FIGS. 4-5, forward movement of sleeve 44a rotates block 46 from the inoperative position in FIGS. 4 and 5 to the operative position in FIGS. 6 and 7. Bearing ring 48 is rotatably mounted on the end of block 46 to permit relative rotation between workpiece Il and block 46 when they are pressed together. In the operative position, workpiece 1I backs up the abutment means on the tool to help absorb 'the energy of the driveable unit 3i?. Hence, movement of the sleeve relative to the barrel between FIGS. 4 and 7 positions, for example, causes not only movement of the abutment flange 45a on the block 4o between inoperative and operative positons but also causes movement of firing pin .i3 between uncocked and cocked positions. As the tool barrel muzzle is pressed against the workpiece, the relative movement moves ring pin 13 to cocked position and moves the abutment means on the tool to the FIG. 7 operative position. After trigger lo has been pulled to release tiring pin i8 to tiring position and driveable unit 3@ is driven to the FIG. 7 position or if the operator desires to return the tool to the safety position with tiring pin 13 uncooked in the FIG. l position, he merely withdraws the tool axially from workpiece il.. The relative movement moves the abutment means on the tool to the FIG. 4 inoperative position and moves the firing pin I to the FIG. l uncooked, safety position. Hence, the automatic operation of this invention cooperates perfectly with the operation of the tool disclosed in said copending application and providing response to thrust against the workpiece and said angle lire control.

In FIGS. 4 and 7, groove 4417 in sleeve 44a is of continuous form but has a helical portion and a longitudinal portion. The helical portion rotates block 4d in response to axial movement of sleeve on barrel 45. The longitudinal portion permits relative axial movement of sleeve 44a on barrel 45 without further rotating block 46 so that the tool may be tired in the same manner as the tool disclosed in said copending application `without diniculty. The barrel length from bearing ring 4S to cocking pin 15a is constant as firing pin IS approaches the cocked position so that ring pin pawl 2) will always align in the same manner with trigger sear lon for proper tiring. Also, when the tool barrel axis is tilted from the perpendicular to the workpiece surface, the angle tire or tilt control described in said copending application still prevents firing of said tool because trigger sear 16a and pawl 2t) do not align at approximately the same tilt since this barrel length remains constant over the range of permissible tilt.

When block 45 is not assembled on the tool, it should be noted that spring 23 in FIG. 7 does not extend far enough forward so that it can be used to move the tool into tiring position. Hence, the tool cannot be ired in unsafe condition without block 46.

Spring 23 provides a form of lost motion connection in the embodiments of FIGS. 1-9 since it with the block and piston serves as resilient energy absorbing means for absorbing the energy of the explosive charge during stopping of piston 32 by permitting axial movement of separate block 36 of FIGS. 1-3 and. of block d6 from FIG. 7 to FIG. 9 relative to its associated barrel wherever there is danger that the fasteners will escape into free iiight, such as when the tool operator `attempts to tire it into material having insufcient resistance to penetration. Normally abutment shoulder 32a is spaced from 36a (FIG. 2) and from ange 46a (FIG. 7). Compare, for example, FIG. 7 showing normal penetration depth with respect to FIG. 9. It should be apparent that 'after reaching full stretch spring 23 integrates the block and barrel and will also provide the same function for block 35 in FIG. 2 and block 46 in FIG. 7.

When the fastener is driven either to the normal penetration position of FIG. 7 or is driven beyond this point until the abutments formed by members 32a and 46a engage, the drivable unit Sii in FIGS. 4-9 can be removed from the bore Se of the tool while the fastener remains embedded in the workpiece.

In FIGS. 4 9, both the fastener 31 and the fastener carrier piston or captive ram 32 are easily disengaged as a unit from the tool after tiring. The tool is removed axially from the driven unit after block 46 is rotated to the inactive position in FIGS. 4 and 5. Then, the piston 32 in FIGS. 4-9 may be unscrewed for reuse and the fastener 35. remains driven in workpiece I1.

Gas ports iSd are also preferably provided in FIG. 4 in the tool barrei to permit gas escape from behind piston 32 before unit 3@ reaches the FIG. 7 position so as to provide the advantages mentioned for ports 15d.

It will also be apparent as the description proceeds, that the tool in FIGS. 1-9 will work in basically the same manner if the fastener can be designed with an outline having the shape of the whole drivable unit so that the unit is one integral manner with the ram or piston portion being integrally a part of the driven fastener so that a separate ram or piston is not required.

In the present disclosure, the tool h'i has in FIGS. 10-13 a captive drivabie unit 5d including fastener 5I detachably connected by screw threads to a fastener carrier, such as the element S2 here shown, which is designated herein as a piston, head or ram. The fastener has a forwardiy projecting piercing portion 51a for penetrating the workpiece after being driven through the vbarrel while the piston has an abutment means or shoulder 52a (the` ieft end of slot 52h in FIGS. 10-13) to be described in further detail hereinafter. The ram or piston is shown as being internally threaded to accept the fasteners, but in the event any fastener has an internally threaded head, its ram or piston may be externally threaded to engage the fastener.

The safety features of the present invention yare not required under normal conditions when there is no danger of having the fastener escape into free fright. During loading of the tool in FIGS. -13, the fastener 51 is screwed into the ram or piston in approximately the FIG. 12 position, and then drivable unit 50 is pushed rearwardly through the barrel 55 to about the FIG. 10 position in the barrel bore 55e until it is close to the seated position of cartridge 17 and is held in this position in any suitable manner, as mentioned for the FIGS. 1-3 tool form.

Then, an explosive charge, such as cartridge I7 in FIGS. 10-13, is also inserted into the breech after which the breech of the tool is closed so that the tool can be moved to firing position against the workpiece Il, as shown by the tool in FIG. 14. After trigger 16 is pulled, the fastener is driven by the tool into the workpiece to its normal and desired penetration shown in FIG. l2 wherein the 5 2! shoulder 52e on the ram normally limits the penetration thereof.

In FIGS. 10-13, the abutment means and its operative connection to the tool takes another form. A crossbar 56 extends transversely through slots or elongated apertures 55a in a modified form of barrel S5 and an elongated aperture or slot 52h in piston 52, elongated in the direction of the barrel axis 4to form a lost motion connection between piston 52 and its associated barrel 55. A helical compression spring 53 and ring 52 are telescoped over each barrel to be located between and to operatively connect Crossbar 56 and its associated barrel by an outwardly extending integral ange SSb on barrel 55 in FIGS. 10-13.

Spring 53 also serves as resilient energy absorbing means for absorbing the energy of the expiosive charge during stopping of piston 52 by permitting axial movenient of Crossbar S6 from FIG. 12 to FIG. 13 relativeto its associated barrel wherever there is danger that the `fastener will escape into free flight, such as when the tool operator attempts to fire it into material having insufficient resistance to penetration. Compare, for example, FIG. 12, showing normal penetration depth, with FIG. 13.

This construction provides greater safety in tool operation as well as more satisfactory setting of the fasteners. It prevents the free escape of a fastener. The tool operator cannot dangerously fire the fastener into free fiight, as a dangerous projectile, by firing the tool into the air instead of against the workpiece. If the workpiece does not have sufficient resistance to penetration, there exists neither the danger that the fastener will emerge from the other side of the workpiece as a projectile in free Hight nor the danger that the fastener will be overdriven beyond the depth control established by the errgagement of the abutment shoulder 52a on the drivable unit and Crossbar 56 on the tool at the barrel muzzle. Substantial inclination of the barrel bore from the normal to the workpiece surface will not cause a ricochet since the tool preferably has said angle tire control and, in any event7 the fastener cannot escape into free night.

When the fastener is driven either to the normal penetration position of FIG. 12 or is driven beyond this point until the abutments formed by members 52a and 56 engage, the fastener 51 in FIGS. 10-13 can be removed from the bore of the tool while the fastener remains embedded in the workpiece.

In FIG. 13, the fastener 51 is easily disengaged from the tool after firing by spinning off or unscrewing the whole tool from the driven fastener 51 so that the tool may be pulled axially therefrom.

Gas ports 55d are also preferably provided in FIG. 10 in the tool barrel to permit gas escape from behind piston 52 before unit 50 reaches the FIG. 12 position so as to provide the advantages mentioned for ports 15d.

The tool in FIG. 14 will be next described. Captive drivable unit Sii therein has the same structure and mode of operation as unit 56 in FIGS. 10-13. The unit and cartridge 17 may ybe loaded into the tool and the unit may be pushed rearwardly in the barrel and held in the barrel bore close to cartridge 17 in any suitable manner, such as mentioned for the FIGS. 10-13 tool form. An abutment 4means on the tool coacts with the abutment means 52a on the piston or ram as the unit attempts to travel substantially beyond the FIG. 12 position in the same manner as when unit 50 attempts to travel substantially beyond the FIG. 12 position.

In FIG. 14, the abutment means and its operative connection to the too-l takes a form similar to that in FIGS. 10-13. Crossbar 56 extends transversely through slots or elongated apertures 55a in the modified form of barrel 55 and an elongated aperture or slot 521i in piston 52, elongated in the direction of the barrel axis to form a lost motion connection between piston 52 and its associated barrel SS. A helical compression spring 53 and ring 52 are telescoped over the barrel to -be located between and to operatively connect cro'ssbar 56 and its associated barrel by an inwardly extending flange 57a on a cap 57 screwed onto sleeve 54a' in FIG. 14. Sleeve 54a surrounds barrel 55 and is generally fixed against axial movement relative to the barrel in the firing position shown in FIG. 14 by having both the barrel muzzle and cap 57 pressed against workpiece 11, but in any event even when not so pressed, the sleeve 54a as in the other embodiments is operatively connected to the barrel through other tool parts shown in FIG. 1 and the aforenoted patent.

Spring S3 in FIG. 14 also absorbs the energy of the explosive charge during stopping in the same manner as spring 53 in FiG. 13.

FIG. 14 also includes resilient means for absorbing the rebound energy of crossbar 55 and spring 53 after the drivable unit has reached a position comparable to FIG. 13. If the tool is fired into the air or into easily penetrated material, compressed spring 53 in FIG. 13 may cause, upon release of its energy, the cross bar 56 to strike the rear end of slots 55a with considerable force. Helical spring 58 is located between and operatively connects crossbar Sn and flange 55h integral with barrel 55 to absorb this rebound energy.

When the fastener is driven either to the normal pene tration positio-n or is driven beyond this point until the abutments, formed by members 52a and 56 engage, the fastener 51 in FIG. 14 can be removed from the bore of the tool while the fastener remains embedded in the workpiece by spinning or unscrewing the whole tool from the driven fastener 51 so that the tool may be pulled axially therefrom.

Gas portsSd' are also preferably provided in FIG. 14 in the tool barrel to permit gas escape from the barrel bore 55e behind piston 52 before unit 5G reaches the FIG. 12 position so as to provide the advantages mentioned for ports 15d.

In all figures of the drawing, the fasteners are shown as being screwed into the piston or captive ram to the full thread depth. However, it is possible to manually adjust the position wherein the safety feature on each of the tools takes effect. The tool operator can preset this distance by adjusting the screw thread engagement between the piston and fastener when the tool is loaded.

Any of these constructions provides greater safety in tool operation as well as more satisfactory setting of the fasteners. It prevents the free escape of a fastener. The tool operator cannot dangerously fire the fastener into free flight, as a dangerous projectile, by firing the tool into the air instead of against the workpiece. If the workpiece does not have sufficient resistance to penetration, there exists neither the danger that the fastener will emerge from the other side of the workpiece as a projectile in free flight nor the danger that the fastener will be overdriven beyond the depth control established by the engagement of the abutments on the drivable unit and on the tool at the barrel muzzle. Substantial inclination of the barrel bore `from the normal to the workpiece surface will not cause a ricochet since the tool preferably has said angle fire control and, in any event, the fastener cannot escape into free ight.

Various changes in details and arrangement of parts can be made by one skilled in the art without departing from either the spirit of this invention or the scope of the appended claims.

What is claimed is:

1. In combination, a power actuated tool and a driveable unit adapted to be driven thereby, said tool including a member providing a passageway so that said power can drive a driveable unit through said passageway toward the discharge end thereof, said driveable unit including a captive head having an abutment means thereon, said head adapted to carry along said passageway a forwardly projecting piercing portion of a fastener for penetrating a workpiece when driven by said tool, an abutment means operatively connected to said member for operatively engaging said rst mentioned abutment means to stop the travel of said unit along said passageway with the piercing portion adapted to travel a predetermined distance beyond the discharge end for workpiece penetration, said second mentioned abutment means including a crossbar extending transversely through apertures in said member and said head with at least one of said apertures being a slot elongated in the length direction of the passageway to form a lost motion connection between said captive head and said member, and a helical compression spring telescoped over said member and operatively engaging said crossbar and an integral outwardly extending flange on said member for absorbing the energy of the driveable unit during stopping of said head by movement of said crossbar relative to said member.

2. An explosive actuated tool for driving a fastener having a workpiece penetrating part, comprising a barrel member having a passageway formed therein and detining a discharge end for said member, piston means movably mounted in said passageway, said fastener being insertable into said passageway at a unit projection extendable substantially ahead of the barrel member for workpiece abutment and said piston means being detachably connectable to said fastener with the workpiece penetrating part forwardly of the former and projecting toward said discharge end, means for discharging an explosive into said passageway effective to drive said piston means and fastener toward said discharge end and force the workpiece penetrating part a normal predetermined distance forwardly of said discharge end, cross bar and slot means defining said distance and `a lost motion connection between said piston means and said barrel member, retainer means operatively connected to said barrel means for providing a rearwardly directed constraint to said piston means through said connection, said lost motion connection being normally inactive during driving of said fastener to said predetermined distance and actuatable in response to a movement of said fastener a distance greater than said predetermined distance to take up the lost motion and transmit said force to said piston means to effect a retardation of its movement toward said discharge end.

3. An explosive actuated tool as defined in claim 2 and including resilient means to provide said rearwardly directed constraint with a variable force in said lost motion connection, said force increasing as said drive extends beyond the predetermined distance.

4. An explosive actuated tool for driving a fastener having a workpiece penetrating part comprising a barrel member having a passageway formed therein and defining a discharge end for said member, a driveable unit movably mounted in said passageway at a unit projection extendable substantially ahead of the barrel member for workpiece abutment and including means for detachable connection to said fastener and a head part having abutment means thereon a space rearwardly of said connection, said fastener being insertable into said passageway and connectable to said driveable unit with the workpiece penetrating part forwardly of the latter and projecting toward said discharge end, means for firing an explosive cartridge into said passageway effective to drive said driveable unit and said fastener toward said discharge end and force the workpiece penetrating part a normal predetermined distance foiwardly of said discharge end, means defining with said space said distance and a lost motion connection between said barrel member and driveable unit comprising a bar element extending through slots transversely across said unit and into said barrel member, energy absorbing means included in said lost motion connection and variably connecting said bar element to said barrel member with increasing force beyond said distance, said lost motion connection being normally inactive while driving said penetrating part of the fastener to said predetermined distance and actuatable in response to an excess movement of said fastener a distance beyond said predetermined distance as to bring said abutment means on said driveable unit into engagement with said bar element, said engagement being eifective to transmit the driving force developed by said cartridge to said energy absorbing means and cause a retardation of the driveable unit during said excess movement toward said discharge end of the barrel member.

5. The tool of claim 4 wherein the means for detachable connection between the fastener and the driveable unit head part is adjustable to axially vary the position of the fastener relative to said part whereby taking effect of the lost motion connection is varied.

6. An explosive actuated tool as defined in claim 4 and wherein a sleeve is operatively attached to the barrel member rearwardly of its discharge end and is formed adjacent said end with detachable inward projection means abuttable with said workpiece and connecting with a helical compression spring comprising the absorbing means to complete the connection between the driveable unit and said `barrel member, and including a rebound resilient element mounted between said barrel member and the bar element and forming a second energy absorbing con nection between said member and element.

7. An explosive actuated fastener driving tool of the hammer type including a barrel member providing a bore from the ybreechto the muzzle of said member, a driveable unit including a piston head mounted in said bore with an abutment and with a nose projection a space forwardly of said abutment adapted with its abutment to be driven through said bore in a working stroke extending a predetermined distance from a retracted position adjacent said breech to a normal forward position adjacent said muzzle, said `projection being extendable substantially ahead of the barrel member for workpiece abutment before said head abutment engages, ,retainer means for preventing escape of said unit from said bore, said means having a part being movably mounted on said member adjacent said muzzle with limited axial relative movement between said part and said barrel member, at least said retainer means part being separate from said barrel member and including on said part a piston stopping abutment normally spaced from said piston head abutment at said normal forward position, said means having an end portion abutable with the workpiece into which said fastener is to be driven, said retainer means including a lost motion connection yieldably connecting said barrel member and at least the latter of said drivable unit and retainer means, said piston head abutment operatively mating with and engaging said stopping abutment to block the travel of said unit beyond said predetermined distance, said connection including said space and distance, and said unit being adapted to said forward position to forwardly project suiciently from said bore a forwardly extending piercing portion of said fastener for impalement into said workpiece abutting said end, whereby in event of overdrive beyond said working stroke engagement between said stopping and mating abutments occurs and the energy of shock is lost in said relative movement between said barrel member and retainer means at least in part at said connection without 12 subjecting said retainer means to excessive impact stress and thereby avoiding fracture of said means and escape of said unit.

8. The tool of claim 7 wherein the connection includes an elastically deformable shock absorbing member including a helical spring telescoped over said barrel member and operatively connecting said barrel member and retainer means.

9. An explosive actuated tool for driving a fastener having a workpiece penetrating part comprising a barrel member having a passageway formed therein and dening a discharge end for said member, a driveable unit movably mounted in said passageway at a unit projection extendable substantially ahead of the barrel member for workpiece abutment and including means for detachable connection to said fastener and a head part having abutment means thereon a space rearwardly of said connection, said fastener being insertable into said passageway and detachably connectable to said driveable unit with the workpiece penetrating part forwardly of the latter and projecting toward said discharge end, means for firing an explosive cartridge into said pasageway effective to drive said driveable unit and said fastener toward said discharge end and force the workpiece penetrating part a normal predetermined distance forwardly of said discharge end, means defining with said space said distance and a lost motion connection between said barrel member and driveable unit comprising a bar element extending transversely across said unit and into said barrel member, a helical spring disposed over the barrel member constituting a variable operative connection between said barrel member and the bar element, said connection being effective to provide to said bar element a variable bias directed rearwardly along said barrel member, said lost motion connection being normally inactive while driving said penetrating part of the fastener to said predetermined distance and actuatable in response to movement of said fastener a distance beyond said predetermined distance as to bring said abutment means on said drivable unit into engagement with sai-d bar element, said bias being effective in response to the actuation of said lost motion connection to resist the driving force developed by said explosive cartridge.

10. The tool of claim 9 wherein the spring is a compression member, and including a rebound compression spring mounted between said barrel member and the bar element and forming a second energy absorbing connection between said member and element.

References @ited in the tile of this patent UNITED STATES PATENTS 

